How supermassive black holes interact with host galaxies

WASHINGTON: Astronomers have discovered strange and unexpected behavior around the supermassive black hole at the heart of the galaxy NGC 5548.

The international team of researchers detected a clumpy gas stream flowing quickly outwards and blocking 90 percent of the X-rays emitted by the black hole. 

This activity could provide insights into how supermassive black holes interact with their host galaxies.

The discovery of the unusual behavior in NGC 5548 is the result of an intensive observing campaign using major ESA and NASA space observatories, including the NASA/ESA Hubble Space Telescope. In 2013 and 2014 the international team carried out the most extensive monitoring campaign of an active galaxy ever conducted. 

There are other galaxies that show gas streams near a black hole, but this is the first time that a stream like this has been seen to move into the line of sight. 

The researchers say that this is the first direct evidence for the long- predicted shielding process that is needed to accelerate powerful gas streams, or winds, to high speeds. 

Jelle Kaastra of the SRON Netherlands Institute for Space Research, who led the research team, said this is a milestone in understanding how supermassive black holes interact with their host galaxies.

Kaastra said, “We were very lucky. You don’t normally see this kind of event with objects like this. It tells us more about the powerful ionized winds that allow supermassive black holes in the nuclei of active galaxies to expel large amounts of matter. In larger quasars than NGC 5548, these winds can regulate the growth of both the black hole and its host galaxy.”